Police have said the band performing at the club lit a flare that ignited flammable soundproofing foam on the ceiling, releasing a deadly combination of cyanide, carbon monoxide, and carbon dioxide.

Prosecutor David Medina told a Tuesday news conference that the nightclub’s two owners and two band members were charged with murder.

‘‘The owners of the nightclub and the members of the band were fully aware of the danger the public faced and could have foreseen the result, but they took no action or were indifferent to the risks,’’ Medina said. ‘‘Fireworks were used in a place that was completely inappropriate for any kind of flame. There was wood, curtain, and unfortunately a lot of people.’’

‘‘There were insufficient and poorly lit exits,’’ he added.

Two firefighters who allegedly tried to show that the nightclub had passed safety inspection tests were charged with evidence tampering. Police have said that minimum safety and fire prevention measures were not in place. An accountant and a former partner of the nightclub were charged with perjury.

The disaster, the worst fire of its kind in more than a decade, raised questions about whether safety can be ensured in such venues as the country prepares to host next year’s World Cup and the 2016 Olympics.